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Test Code CAFF Caffeine, Serum


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL Serum

Collection Instructions:

1. Within 2 hours of collection, centrifuge the specimen.

2. For serum gel tubes, serum may sit on the gel or be aliquoted into a plastic vial.

3. For red top tubes, aliquot serum into a plastic vial immediately after centrifugation.


Useful For

Monitoring caffeine therapy in neonates

 

Assessing caffeine toxicity in neonates

Method Name

Enzyme Multiplied Immunoassay Technique (EMIT)

Reporting Name

Caffeine, S

Specimen Type

Serum

Specimen Minimum Volume

Serum: 0.25 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen (preferred) 28 days
  Ambient  72 hours
  Refrigerated  72 hours

Reject Due To

Gross hemolysis Reject

Clinical Information

Caffeine is used to treat apnea of prematurity that occurs in newborn infants, the most frequent complication seen in the neonatal nursery.

 

In neonates, caffeine has a half-life that ranges from approximately 3 to 4 days, which is much longer than in adults (typically 4-6 hours) due to the immaturity of the neonatal liver. This requires that small doses be administered at much longer intervals than would be predicted based on adult pharmacokinetics.

 

The volume of distribution of caffeine is 0.8 to 0.9 L/kg (infants) or 0.6 L/kg (adults) and the drug is approximately 36% protein bound.

 

Toxicity observed in neonates is characterized by central nervous system and skeletal muscle stimulation and bradycardia. These symptoms are seen in adults at lower levels than in neonates, suggesting that neonates have much greater tolerance to the drug.

Reference Values

Therapeutic: 8.0-20.0 mcg/mL

Critical value: ≥30.0 mcg/mL

Day(s) Performed

Monday through Saturday

Report Available

Same day/1 to 2 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

80155

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.